Support for continuity of tunnel communications for mobile nodes having multiple care of addressing

ABSTRACT

The present invention solves communication disruption problems during the hand-off transition period by using a pre-handoff registration of a new foreign agent on behalf of the mobile node The pre-handoff registration message should: (1) identify itself as a pre-hand off registration message, (2) indicate direction of traffic for the pre-handoff registration time period, and (3) specify a lifetime or time period when the pre-handoff registration request will continue to be considered valid The local mobility anchor will accept traffic using the pre-handoff registration care-of address depending on the directionality indicator, but the communication traffic to or from the mobile node will not be disrupted during the transition period. Because the care-of address for the mobile node on the new foreign network can be used to direct communication traffic to or from the mobile node during this transition time period, no disruption of service will be encountered.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.13/661,203, filed Oct. 26, 2012, which is a continuation of U.S.application Ser. No. 12/744,258, filed on May 21, 2010, which is aNational Phase Entry of PCT/US2008/12951, filed on Nov. 20, 2008, whichclaims the benefit of prior U.S. Provisional Patent Application Ser.Nos. 60/989,546 filed on Nov. 21, 2007 and 60/991,023 filed on Nov. 29,2007, which are all incorporated herein by reference, as if set forthfully and completely herein.

TECHNICAL FIELD OF THE INVENTION

A method for supporting assuring continuity of tunneled communicationswith a mobile node on a communication system using pre-handoffregistration indicators or options.

BACKGROUND OF THE INVENTION

IP-based mobile systems provide for communication between at least onemobile node and a wireless communication network. The term “mobile node”includes a mobile communication unit (e.g., mobile terminal, “smartphones”, nomadic devices such as laptop PCs with wireless connectivity,as described in greater detail below). Among other elements, thewireless communication system includes a home network and a foreignnetwork. The mobile node may change its point of attachment to theInternet through these networks, but the mobile node will always beassociated with a single home network for IP addressing purposes. Thehome network includes a home agent and the foreign network includes aforeign agent—both of which control the routing of information packetsinto and out of their network. Generally, there may also be acorrespondence node associated with the system, which may be a mobile orfixed node located on one of the networks that communicates with themobile node.

The mobile node, home agent and foreign agent may be called differentnames depending on the nomenclature used on any particular networkconfiguration or communication system. For instance, a “mobile node”encompasses PC's having cabled (e.g., telephone line (“twisted pair”),Ethernet cable, optical cable, and so on) connectivity to the wirelessnetwork, as well as direct wireless connectivity to the cellularnetwork. Direct wireless connectivity to a cellular network is supportedby various makes and models of mobile terminals (“cell phones”) havingvarious features and functionality, such as Internet access, e-mail,messaging services, and the like. Mobile nodes are sometimes called auser equipment, mobile unit, mobile terminal, mobile device, or similarnames depending on the nomenclature adopted by particular systemproviders.

A home agent may also be referred to as a local mobility anchor, homemobility manager, home location register, and a foreign agent may bereferred to as a mobile access gateway, serving mobility manager,visited location register, and visiting serving entity. The terms mobilenode, home agent and foreign agent are not meant to be restrictivelydefined, but could include other mobile communication units orsupervisory routing devices located on the home or foreign networks.Foreign networks can also be called serving networks.

Registering the Mobile Node

Foreign agents and home agents periodically broadcast an agentadvertisement to all nodes on the local network associated with thatagent. An agent advertisement is a message from the agent on a networkthat may be issued under the Mobile IP protocol (RFC 2002) or any othertype of communications protocol. This advertisement should includeinformation that is required to uniquely identify a mobility agent (e.g.a home agent, a foreign agent, etc.) to a mobile node. Multipleinterfaces may also be supported on a single or multiple foreignnetworks, which can include the different communication access types802.11d, 802.11g, HRPD, WiFi, WiMax, CDMA, or LTE. Mobile nodes examinethe agent advertisement and determine whether they are connected to thehome network or a foreign network.

The mobile node will always be associated with its home network andsub-network for IP addressing purposes and will have information routedto it by routers located on the home and foreign network. If the mobilenode is located on its home network, information packets will be routedto the mobile node according to the standard addressing and routingscheme.

If the mobile node is visiting a foreign network, however, the mobilenode obtains appropriate information from the agent advertisement, andtransmits a registration request message (sometimes called a bindingupdate request) to its home agent through the foreign agent. Theregistration request message will include a care-of address for themobile node. A registration reply message (also called a binding updateacknowledge message) may be sent to the mobile node by the home agent toconfirm that the registration process has been successfully completed.

Care-of Addressing and Discontinuity Problems

As part of the registration process, the mobile node maintainsconnectivity with the home agent or local mobility anchor through theuse of a “care-of address.” This care-of address is registered with thehome agent or local mobility anchor in a table, sometimes called aBinding Cache Entry Table. The registered care-of address identifies theforeign network where the mobile node is located, and the home agent orlocal mobility anchor uses this registered care-of address to forwardinformation packets to the foreign network for subsequent transfer ontothe mobile node.

If the home agent or local mobility anchor receives an informationpacket addressed to the mobile node while the mobile node is located ona foreign network, the home agent or local mobility anchor will transmitthe information packet to the mobile node's current location on theforeign network using the applicable care-of address. This isaccomplished by forwarding the information packet to the care-of addresswhere the foreign network will receive the information packet, andforward the information packet to the mobile node on the foreignnetwork. During these communications, the transmission of communicationpackets between the foreign network and the home agent or local mobilityanchor will be performed using a tunneling communication protocol.

The registered care-of address identifies the foreign network where themobile node is located, and the home agent or local mobility anchor alsouses this registered care-of address to forward information packetsreceived from the mobile node located on the foreign network. In thissituation, the mobile node may transmit information and communicationpackets back through the foreign agent to the home agent or localmobility anchor for further processing and transmission to other nodeson the system, such as the correspondence node. The source of theinformation packets will be identified on the mobile node's packets asthe mobile node's care-of address.

The home agent or local mobility anchor will confirm that the mobilenode's communications are being transmitted from a valid care-of addressfor the mobile node before routing, processing, and further transferringthe packets received from the mobile node. If the home agent receives aninformation packet that does not have a valid care-of address as itssource, the packets will not be processed further. If the care-ofaddress is valid, the information packet will then be forwarded androuted to the destination by the home agent or local mobility anchor.These communications are sometimes referred to a “tunneled”communication between the foreign network and the home network.

A mobile node may transition and move from one foreign network toanother foreign network. Each foreign network is identified by adifferent care-of address, so the transition of the mobile node from oneforeign network to a new foreign network requires a modification of thecare-of addresses registered for the mobile node at the home agent orlocal mobility anchor. During this modification of the care-ofaddressing resulting from the mobile node transition from one foreignnetwork to another foreign network, problems are sometimes encounteredwith the maintaining the continuity of the tunneled messagetransmissions to and from the mobile node through the home agent orlocal mobility anchor.

For instance, messages addressed to the new care-of address for the newforeign network may not be properly transmitted to the mobile node bythe home agent or local mobility anchor until the hand-off to the newforeign network has been fully completed. In fact, prior to the hand-offto the new foreign network being fully completed, communication packetsaddressed to the new foreign network may be dropped or communicationpackets may be misdirected to the old foreign network care-of address,both of which will result in a disruption of the continuity of thecommunication to the mobile node.

Moreover, mobile node information and communication packets being sentfrom the new foreign network may not be properly recognized because thecare-of addressing for the new foreign network has not been registeredwith the home agent or local mobility anchor. In this situation, thehome agent or local mobility anchor may refuse to accept communicationpackets from the mobile node on the new foreign network prior to thehand-off being fully completed to the new foreign network because thecare-of address for the new foreign network is not recognized by thehome agent or local mobility anchor as a valid source for suchcommunication packets. These continuity problems cause communicationdisruption, dropped packets and interruption in continuous service. Itis a primary objective of this invention to provide care-of addressingsupport and continuity of tunneled communication to and from a mobilenode where the handover to a new foreign network is being initiated.

SUMMARY OF THE INVENTION

The present invention solves these communication disruption problemsduring the hand-off transition period by using a pre-handoffregistration of a new foreign agent on behalf of the mobile node. Thepre-handoff registration message should: (1) identify itself as apre-hand off registration message, (2) indicate direction of traffic forthe pre-handoff registration time period, and (3) specify a lifetime ortime period when the pre-handoff registration request will continue tobe considered valid. The pre-handoff registration may use a flagindicator or option in a registration message.

The home agent or local mobility anchor will process the pre-handoffregistration by adding appropriate values to its Binding Cache EntryTable, which will recognize the care-of addressing for the new foreignnetwork as a valid address associated with the mobile node during thespecified lifetime period. The local mobility anchor will accept trafficusing the pre-handoff registration care-of address depending on thedirectionality indicator, but the communication traffic to or from themobile node will not be disrupted during the transition period. Becausethe care-of address for the mobile node on the new foreign network canbe used to direct communication traffic to or from the mobile nodeduring this transition time period, no disruption of service will beencountered and continuity of service to and from the mobile node willbe maintained.

If the lifetime expires before either of these actions occur, thelifetime time period can be over-ridden or updated to extend the timeperiod prior to completion of the hand-off when the pre-handoff requestwill still be recognized as valid. The pre-handoff registration statusof the care-of address can be recognized as the registered care-ofaddress after the new foreign agent sends a proper handoff registrationrequest to complete the hand-off procedure or the former foreign agentrequests revocation of its prior registration with the home agent orlocal mobility anchor.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention will become more readilyunderstood from the following detailed description and appended claimswhen read in conjunction with the accompanying drawings in which likenumerals represent like elements and in which:

FIG. 1 is a mobile IP-based communication system as used in the presentinvention; and,

FIG. 2 is a message sequence for the mobile IP-based communicationsystem as used in the present invention.

The objects and features of the invention will become more readilyunderstood from the following detailed description and appended claimswhen read in conjunction with the accompanying drawings in which likenumerals represent like element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, the overall architecture of the IP-based mobile system isshown with a mobile node 125, a home network 110 and foreign networks130 and 150, respectively. As shown in FIG. 1, the home network 110 hasa home agent or local mobility anchor 113. The local mobility anchor 113is coupled to the mobility agent gateway 155 on foreign network 150 bycommunication link 112, and local mobility anchor 113 is coupled to themobility agent gateway 135 on foreign network 130 by communication link115.

A correspondence node CN 175 is coupled to the home network 110 bycommunication link 170, which can be a connection composed of wire linelinks, the Internet and/or wireless connections. The correspondent node175 can include a source of data, voice over IP, or other electroniccommunication data that is transmitted to or from the mobile node 125.In the present invention, the mobile node 125 may have an on-goingcommunication session with the correspondent node 175 that needs to bemaintained when the mobile node is attached to foreign network 130 orthe mobile node is transitioning and moving to be connected to the newforeign network 150.

The mobility agent gateway 135 is coupled to the mobile node 125 throughthe radio access system comprised of the base station transceiver 139coupled to the antenna/transmitter 137 through the wirelesscommunication link 127. This link represents the existing foreignnetwork supporting the communication with the mobile node 125. In thepresent invention, the mobile node 125 is transition its connection fromthe foreign network 130 to the foreign network 150.

When connected to the foreign network 150, the mobility agent gateway155 will be coupled to the mobile node 125 through the radio accesssystem comprised of the base station transceiver 190 connected by link191 to the antenna/transmitter 192 and a wireless communication link180. The mobility access gateways 155 and 135 may work in conjunctionwith base station transceivers 190 and 139, respectively. The basestation transceivers 190 and 139 may also be called evolving nodebasestation (eNB) depending on the nomenclature used by the particulartechnology supporting the system.

Mobile node 125 is shown electronically coupled to the foreign networks150 and 130 via the wireless communication link 180 and 127,respectively. The mobile node 125, however, can communicate with anytransceiver or access network coupled to a foreign network. That is,communications links 180 and 127 are radio transmitted links, but theselinks can be composed of any connection between two or more nodes on anetwork or users on networks or administrative domains. The mobilityagent gateway 155 could also be coupled to the mobile node 125 using asecond communication access type, such as WiMax or WiFi, which issupported by the interface 141 and wireless communication link 157.

The terms Local Mobility Anchor, home agent, and foreign agent may be asdefined in the Mobile IP Protocol (RFC 2002), but these agents are notrestricted to a single protocol or system. In fact, the term home agent,as used in this application, can refer to a home mobility manager, homelocation register, home serving entity, or any other agent at a homenetwork 110 having the responsibility to manage mobility-relatedfunctionality for a mobile node 125. Likewise, the term mobility agentgateway, as used in this application, can refer to a foreign agent,serving mobility manager, visited location register, visiting servingentity, or any other agent on a foreign network having theresponsibility to manage mobility-related functionality for a mobilenode 125.

In the mobile IP communications system shown in FIG. 1, the mobile node125 is identified by a permanent IP address. While the mobile node 125is coupled to its home network 110, the mobile node 125 receivesinformation packets like any other fixed node on the home network 110.When located away from the home network, the mobile node 125 can alsoconnect itself to a foreign network, such as network 130 or 150, tomaintain connectivity with the home network through those foreignnetworks.

The mobile node 125 keeps the local mobility anchor 113 informed of itscurrent location, or foreign network association, by registering acare-of address with the local mobility anchor 113. Essentially, thecare-of address represents the foreign network where the mobile node 125is currently located. When located on foreign network 130 or 150, thehome network 110 sends data communications to the mobile node 125 by“tunneling” the communications to the foreign network 130 or 150 usingthis care-of addressing. If the local mobility anchor 113 receives aninformation packet addressed to the mobile node 125 while the mobilenode 125 is located on a foreign network 130, the local mobility anchor113 will “tunnel” the information packet to foreign network 130 forsubsequent transmission to mobile node 125.

The foreign agent 135 receives information packets for the mobile node125 after the information packets have been forwarded to the foreignagent 135 by the local mobility anchor 113. Moreover, the foreign agent135 serves as a default router for out-going information packetsgenerated by the mobile node 125 while connected to the foreign network130. When the local mobility anchor 113 receives information packetsfrom the mobile node 125 through the default router foreign agent ormobility agent gateway 135, it will confirm whether the transmission isbeing initiated from a registered foreign network 130 for the mobilenode by confirming the care-of address registered for the mobile node125.

The communication link 115 between mobility agent gateway 135 on foreignnetwork 130 and the local mobility anchor or home agent 113 isconfigured as an IP-in-1P tunnel after being set up using a proxybinding update request and a proxy binding acknowledge message. Uponsetting up the care-of addressing on the tunneled communicationconnection with the foreign network, the local mobility anchor or homeagent 113 maintains appropriate address entries on a Binding Cache EntryTable, which includes the care-of address for the mobility agent gatewayand the home network prefix address.

When the mobile node 125 needs to transition to the new foreign network150 because of its movement, the communication link 112 is used tocommunicate with the mobile node 125 over the new foreign network 150.In that instance, communication link 112 will also be configured as anIP-in-IP tunnel. Upon receiving a proxy binding update request thatrequests registration of the mobile node with the new foreign network150, the local mobility anchor 113 will set up the care-of addressing onthe tunneled communication connection with the foreign network 150, andthe local mobility anchor or home agent 113 will modify the care-ofaddress entry on a Binding Cache Entry Table.

The local mobility anchor 113 will register the new care-of address forthe mobile node on the new foreign network 150 by registering themobility agent gateway 155 and the home network prefix address on theBinding Cache Entry Table maintained by the home agent or local mobilityanchor 113. The local mobility anchor 113 will respond to the proxybinding update request with a proxy binding acknowledge message sent tothe mobility agent gateway 155.

After the hand-off procedure is completed, the local mobility anchor 113receives an information packet addressed to the mobile node 125 whilethe mobile node 125 is located on a foreign network 150, and the localmobility anchor 113 will “tunnel” the information packet to foreignnetwork 150 for subsequent transmission to mobile node 125. The foreignagent 155 receives information packets for the mobile node 125 after theinformation packets have been forwarded to the foreign agent 155 by thelocal mobility anchor 113. Moreover, after completion of the hand-offprotocol, the foreign agent 155 serves as a default router for out-goinginformation packets generated by the mobile node 125 while connected tothe foreign network 150. When the local mobility anchor 113 receivesinformation packets from the mobile node 125 through the default routerforeign agent or mobility agent gateway 155, it will confirm whether thetransmission is being initiated from a registered foreign network 150for the mobile node by confirming the care-of address registered for themobile node 125.

This registration process and completion of the hand-off protocol takesa finite time period to complete, and there may be a need to maintainactive connectivity of the mobile node with the home agent or localmobility anchor 113 during this transition and registration period. Ifconnectivity is not maintained during the transition period, packetsaddressed to the mobile node 125 may be misdirected or packets beingsent by the mobile node 125 may be dropped.

To maintain connectivity of the mobile node 125 with the local mobilityanchor 113 and prevent disruption of the mobile node's 125communications, the present invention allows for the use of apre-handoff registration message that is sent to the local mobilityanchor 113 prior to completion of the hand-off protocol. Thepre-registration request message can be sent to the local mobilityanchor 113 by the mobility agent gateway 155 for the foreign network 150after the mobility agent gateway 155 realizes that the mobile node 125is moving into the domain of the foreign network 150. The local mobilityanchor 113 will register the new foreign network 150 and a provisionalcare-of address will be assigned to the mobile node 125 through theforeign network 150 during the transition period prior to completion ofthe hand-off procedure. Appropriate registrations of the provisionalcare-of address for the mobile node 125 will be made on the localmobility anchor's 113 Binding Cache Entry Table.

The pre-handoff registration message can be composed of a proxy bindingupdate message, but it should: (1) identify itself as a pre-hand offregistration message, (2) indicate direction of traffic for thepre-handoff registration time period, and (3) specify a lifetime or timeperiod when the pre-handoff registration request will continue to beconsidered valid. The pre-handoff registration may specify these detailsby using flag indicators or options in the proxy binding updateregistration message. The flag indicators for the pre-handoffregistration request may be predetermined fields in the proxy bindingupdate request message, which indicator flags specifying data fields andtime periods explicitly or indirectly through associated representativevalues. A handoff indicator option may also be used where a new valueindicates that the proxy binding update request is a pre-handoffregistration message, the directionality of the traffic is provided anda lifetime is specified as part of the additional option information.

The lifetime will indicate how long the local mobility anchor 113 shouldrecognize the provisional care-of address for the mobile node 125 on thenew foreign network 155, and the direction of the traffic for thepre-handoff registration time period will specify whether the localmobility anchor 113 will allow “uplink traffic” from the mobile node tobe sent through the new foreign network 150 during the transitionperiod, “downlink traffic” to the mobile node to be sent to the newforeign network 150 during the transition period, or both “uplink” and“downlink” traffic, which is also called “bidirectional traffic.”

The local mobility anchor 113 will accept traffic using the provisionalcare-of address depending on the directionality indicator, but thecommunication traffic to or from the mobile node will not be disruptedduring the transition period. If the directionality is “uplink traffic,”the local mobility anchor will recognize as valid traffic having theprovisional care-of addresses being sent from new foreign network 150and the former foreign network 130. If “uplink traffic” is thedirectionality indicated, all traffic to the mobile node 125 will besent to the old care-of address associated with the mobility agentgateway 135 on foreign network 130. If the directionality is “downlinktraffic,” the provisional care-of address for the mobility agent gateway155 on the new foreign network 150 will be used for all traffic sent tothe mobile node 125. If “bidirectional” traffic is indicated, alltraffic to and from the mobile node will be directed through theprovisional care of address associated with the mobility agent gateway155 on the foreign network 150.

The home agent or local mobility anchor 113 will process the pre-handoffregistration by adding appropriate values to its Binding Cache EntryTable, which will recognize the care-of addressing for the new foreignnetwork as a valid address associated with the mobile node during thespecified lifetime period. The local mobility anchor 113 will respond tothe mobility agent gateway 155 with a proxy binding acknowledge messageconfirming the pre-handoff registration of the new care-of address atthe local mobility anchor 113. When communications packets containingthe provisional care-of address for the new foreign network 150 arereceived by the local mobility anchor 113, these packets will berecognized as proper and processed appropriately to make sure theconnectivity of the mobile node 125 is maintained. Because theprovisional care-of address for the mobile node 125 on the foreignnetwork 150 can be used to direct communication traffic to or from themobile node 125, no disruption of service will be encountered andcontinuity of service to and from the mobile node 125 will bemaintained.

If the lifetime of the pre-handoff registration expires before theproper handoff protocol is completed, the lifetime time period can beover-ridden or updated to extend the time period prior to completion ofthe hand-off when the pre-handoff request will still be recognized asvalid. The update of the pre-handoff registration status can also modifythe provisional care-of address into a formal care-of address to beassociated with the new foreign network. The pre-registration care-ofaddress can also be modified by allowing it to serve as the formalcare-of address after expiration of the lifetime or after an overriderequest is received by the local mobility anchor 113.

The pre-handoff registration status of the care-of address can berecognized as the registered care-of address after the new foreign agentsends a proper handoff registration request to complete the hand-offprocedure or the former foreign agent requests revocation of its priorregistration with the home agent or local mobility anchor. While thesetransitions can modify the pre-handoff registration into a formalhand-off registration, it may be more appropriate for the mobility agentgateway 155 to still send a formal hand-off registration message to thelocal mobility anchor to assure proper registration of the mobile node125 on the foreign network 155. After completion of the hand-offprotocol, the directionality of traffic will be “bidirectional” with thetraffic being sent in both directions to the new care-of address for thenew foreign network 150.

As shown in FIG. 2 and with reference to the system shown in FIG. 1, themessage sequence for pre-handoff registration message is initiated bythe mobile node 125 when it send a message 210 to the evolving nodebasestation 190 indicating that it is entering its service area. Theevolving node basestation 190 sends a message 220 to the mobility agentgateway 155 on foreign network 150 indicating the future movement of themobile node 125 onto the foreign network 150. Prior to the transmissionof a handoff request or prior to the completion of the hand-off protocolfor the transition of the mobile node 125 onto the foreign network 150,the mobility agent gateway 155 sends a pre-handoff registration requestmessage 230 in the form a proxy binding update request to the localmobility anchor 113.

The proxy binding update request message 230 should: (1) identify itselfas a pre-hand off registration message, (2) indicate direction oftraffic for the pre-handoff registration time period, and (3) specify alifetime or time period when the pre-handoff registration request willcontinue to be considered valid. The pre-handoff registration requestmessage 230 may specify these details by using flag indicators oroptions in the proxy binding update registration message.

The lifetime will indicate how long the local mobility anchor 113 shouldrecognize the provisional care-of address for the mobile node 125 on thenew foreign network 155, and the direction of the traffic for thepre-handoff registration time period will specify whether the localmobility anchor 113 will allow “uplink traffic” from the mobile node tobe sent through the new foreign network 150 during the transitionperiod, “downlink traffic” to the mobile node to be sent to the newforeign network 150 during the transition period, or both “uplink” and“downlink” traffic, which is also called “bidirectional traffic.”

The home agent or local mobility anchor 113 will process the pre-handoffregistration by adding appropriate values to its Binding Cache EntryTable, which will recognize the care-of addressing for the new foreignnetwork as a valid address associated with the mobile node during thespecified lifetime period. After registration of the provisional care-ofaddress for the mobile node, the local mobility anchor 113 will respondto the mobility agent gateway 155 with a proxy binding acknowledgemessage 260 confirming the pre-handoff registration of the new care-ofaddress at the local mobility anchor 113. The mobility agent gatewaywill confirm the pre-handoff registration process with the mobile node125 by sending a message 270 to the evolving node basestation 190, whichis sent onto the mobile node 125.

When communications packets containing the provisional care-of addressfor the new foreign network 150 are received by the local mobilityanchor 113, these packets will be recognized as proper and processedappropriately to make sure the connectivity of the mobile node 125 ismaintained. Because the provisional care-of address for the mobile node125 on the foreign network 150 can be used to direct communicationtraffic to or from the mobile node 125, no disruption of service will beencountered and continuity of service to and from the mobile node 125will be maintained.

Modifications of the present invention allow for the directionalityindicators to be modified to accommodate different designations ordirections of traffic for “uplink” and “downlink” traffic. Further, itshould be understood that a care-of address may refer to a proxy care-ofaddress in the specification and the claims, and the mobility agentgateway 113 may de-register mobile node proxy bindings from the initialmessaging for as long as security associations are valid and maintained.The mobility agent gateway may also update current mobile proxy bindingsor use a binding revocation indication message instead of ade-registration message to delete or modify the mobile node 125bindings.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.

Having described the invention, we claim:
 1. A method for registering amobile node on a foreign network during a hand-off transitioncomprising: at a node of a home network: receiving a pre-handoffregistration request message after the mobile node has initiated aconnection to said foreign network but prior to completion of a hand-offto the foreign network, said pre-handoff registration request messageincluding a lifetime time period indicator; after processing thepre-handoff registration request, transmitting a registration responseconfirming the pre-handoff registration for the transitional lifetimetime period; and using the provisional care-of address to processcommunication packets associated with the mobile node.
 2. The method ofclaim 1, wherein the pre-handoff registration request further comprisesa directionality indicator specifying the direction of trafficassociated with the foreign network that will be processed during thelifetime time period, wherein processing the communication packetsassociated with the mobile node is based on the directionalityindicator.
 3. The method of claim 2, wherein the pre-hand offregistration request specifies uplink traffic as its directionality,which means the local mobility anchor will process communication packetshaving the provisional care-of addresses being sent from the foreignnetwork on behalf of the mobile node.
 4. The method of claim 2, whereinthe pre-hand off registration request specifies downlink traffic as itsdirectionality, which means the local mobility anchor will forwardcommunication packets having the provisional care-of addresses to theforeign network sending the pre-handoff registration message for themobile node.
 5. The method of claim 1, wherein the pre-handoffregistration request lifetime indicator can be modified to extend thetime period for the validity of the provisional care-of address.
 6. Themethod of claim 1, further comprising: after completion of hand-off tothe foreign network, using the provisional care-of address as thecare-of address for the future processing of all communication packetsbeing sent from or sent to the mobile node.
 7. The method of claim 1,wherein the node comprises a home agent.
 8. A node in a home networkconfigured to register a mobile node on a foreign network during ahand-off transition comprising: communication circuitry; and processinghardware coupled to the communication circuitry, wherein the processinghardware and the communication circuitry are configured to: receive apre-handoff registration request message after the mobile node hasinitiated a connection to said foreign network but prior to completionof a hand-off to the foreign network, said pre-handoff registrationrequest message including a lifetime time period indicator; afterprocessing the pre-handoff registration request, transmit a registrationresponse confirming the pre-handoff registration for the transitionallifetime time period; and using the provisional care-of address toprocess communication packets associated with the mobile node.
 9. Thenode of claim 8, wherein the pre-handoff registration request furthercomprises a directionality indicator specifying the direction of trafficassociated with the foreign network that will be processed during thelifetime time period, wherein processing the communication packetsassociated with the mobile node is based on the directionalityindicator.
 10. The node of claim 9, wherein the pre-hand offregistration request specifies uplink traffic as its directionality,which means the local mobility anchor will process communication packetshaving the provisional care-of addresses being sent from the foreignnetwork on behalf of the mobile node.
 11. The node of claim 9, whereinthe pre-hand off registration request specifies downlink traffic as itsdirectionality, which means the local mobility anchor will forwardcommunication packets having the provisional care-of addresses to theforeign network sending the pre-handoff registration message for themobile node.
 12. The node of claim 8, wherein the pre-handoffregistration request lifetime indicator can be modified to extend thetime period for the validity of the provisional care-of address.
 13. Thenode of claim 8, wherein the processing hardware and communicationcircuitry is further configured to: after completion of hand-off to theforeign network, use the provisional care-of address as the care-ofaddress for the future processing of all communication packets beingsent from or sent to the mobile node.
 14. The node of claim 8, whereinthe node comprises a home agent.
 15. A method for registering a mobilenode on a foreign network during a hand-off transition comprising: at anode: transmitting a pre-handoff registration request message after themobile node has initiated a connection to said foreign network but priorto completion of a hand-off to the foreign network, said pre-handoffregistration request message including a lifetime time period indicator;after processing the pre-handoff registration request, receiving aregistration response confirming the pre-handoff registration for thetransitional lifetime time period, wherein after receiving theregistration response, the provisional care-of address is used toprocess communication packets associated with the mobile node.
 16. Themethod of claim 15, wherein the pre-handoff registration request furthercomprises a directionality indicator specifying the direction of trafficassociated with the foreign network that will be processed during thelifetime time period, wherein processing the communication packetsassociated with the mobile node is based on the directionalityindicator.
 17. The method of claim 15, wherein the pre-handoffregistration request lifetime indicator can be modified to extend thetime period for the validity of the provisional care-of address.
 18. Anode involved in registering a mobile node on a foreign network during ahand-off transition comprising: communication circuitry; and processinghardware coupled to the communication circuitry, wherein the processinghardware and the communication circuitry are configured to: transmit apre-handoff registration request message after the mobile node hasinitiated a connection to said foreign network but prior to completionof a hand-off to the foreign network, said pre-handoff registrationrequest message including a lifetime time period indicator; afterprocessing the pre-handoff registration request, receive a registrationresponse confirming the pre-handoff registration for the transitionallifetime time period, wherein after receiving the registration response,the provisional care-of address is used to process communication packetsassociated with the mobile node.
 19. The node of claim 18, wherein thepre-handoff registration request further comprises a directionalityindicator specifying the direction of traffic associated with theforeign network that will be processed during the lifetime time period,wherein processing the communication packets associated with the mobilenode is based on the directionality indicator.
 20. The node of claim 18,wherein the pre-handoff registration request lifetime indicator can bemodified to extend the time period for the validity of the provisionalcare-of address.